Method of hollow grinding razor blades



Nov. 25, 1924- v 1,516,832

, 'r. c. SHEEHAN METHOD OEMHOLLOW GRiNDING RAZQR BLADES Filed Feb. 9, 1921 NVENTOR ww M,%4%

BY n ATTORNEYS Patented Nov. 25, 1924.

UNITED STA-T es 1,516,832 PATENT OFFICE. v

THOMAS c. SHEEHAN, or UPPER MONTCLAYIR, NEW JERSEY, ASSIGNO'R T DURHAM DUPLEX RAZOR, COMPANY, or NEW YORK," N. Y., A CORPORATION or NEW YORK.

METHOD or HOLLOW GRINDING Rhzon BLADES. I

Application filed February a, 1921. Serial is. 443,515.

"of New Jersey, have invented a new and useful Improvement in Methods of Hollow Grinding Razor Blades, of which the following is a specification.

This invention relates to hollow-ground razor blades and a method of making the same, and the apparatus shown in this application is claimed in'my copending application, Serial No. 448.516, filed February 9th, 1921, for which Patent No. 1,425,798

was granted Aug. 15, 1922. 7

When other properties are equal, i the efficiency of such razor blades depends upon their form, particularly their crosssectional form; and although it has long been considered highly desirable that'the form of each blade of a particular type be exactly like all others-of thattype, it is well known that even the most carefully made razor blades vary in efficiency and this .highly desirable result has never been attained.

It has been discovered that the cause of the'difiiculty lies in unequal and otherwise. imperfect grinding resulting from the useof the various grinding methods heretofore known. In all known methods, the inevitable wearing away of the grinding instrument afi'ected the form of hollowground blades in such manner as to render impossible the manufacture of an indefinite number of blades exactly alike in form; It

has been further discovered that the difficulty can be overcome by positioning a blade with one surface to be ground slightly within a constant circle wholly unaffected by the wearing away of the grinding instrument, the radius ofsaid circle being determined by and equal to the radius of said surface when ground, which radius determines the concavity of the blade, then grinding said surface. to said circle, and

then repeating the grinding operation on the opposite side of the blade; thus pro- -ducinga razor blade the opposite surfaces of which are equally hollow-ground to a constant circle the radius of which is equal to the radius of each surface,-whereby each blade will be exactly like all others made by the same. method. The underlying object of the present invention is the production of razor blades of the efii'cient type just described.

In the accompanying drawings,rwhichillustrate one form ofapparatusby means of which thenew method may be carried highly into effect, and which form a part ofthis specification and in which like characters of reference indicate the same or like parts,

Iiig. 1 is an end elevation, partly in section, of an apparatus-designed to carry the invention into effect; Fig. 2 is anenlarged longitudinal sectional viewv of the blade positioning chuck shown-in Fig. '1, andyil- .lustrating a blade locked in said chuck;

ground, and then grinding said surface to said circle. .As the method is ordinarily employed, aseries of blades is positioned with the surfaces to be ground slightly within the same constant circle the radius OfWhlCh is equal to-the radius of eachof said surfaces when ground, and then grinding said surfaces-to said circle in asingle operation; after which the blades are reversely positioned and the opposite sur faces are ground to'the constant circle in like manner.,

w Referring to the drawings, which, as before stated, illustrate one apparatus adapted to carry the method into efiect, 4 is a chuck provided with a series of recesses 5 cut in its inner wall and each adapted to receive a razor blade -6, the surface of each blade being positioned slightly withina constant circle. 7 withinjthe chuck. As shown, each blade is held in position by means of ledges 8 formed on the ends ofstuds 9 threaded or otherwise-held in the wall of the chuck, and coactingeccentricclamping devices 10 also threaded in the. walls of the chuck. The .chuck fits in a rabbeted seat- 11" formed on a hollowsupport 12 adapted to' receive the shanks of the blades and provided with a gear 13 driven by a pinion 14 deriving its motion from a suitable source of power,

not shown. I

When the blades are positioned in the chuck and the chuck is mounted in the support 12, one surface of each blade to be ground is acted on by a grinding wheel 15 ment is produced by the coaction of a rack secured to the head, and a pinion 21. The

. rack 20 is'slidably mounted in an adjustable' block 22 laterally dove-tailed on a fixed bar 23 supported by a bracket 24 rising from the main frame 25 of the apparatus. The pinion 21 is mounted on a 'shortshaft 26 journaled in lugs 27 depend- I ing from the adjustable block 22. The block 22 is adjustedbymeansof two set screws 1 28 threaded in lugs 29 secured to the bracket 24 before referred to- Only one of these set screws is shown, but itwill be readily understood that the other is on the opposite side of the block 22, and that the block is adjusted by and locked between the two, in a. well known 'manner.

bar in-' the shaft-26, not shown but of the type usual in such mechanisms. i

By' means of the adjusting screws 28, the.

grinding Wheel 15, shown in full lines in Fig. 1 and indicated by the broken line 15 in F i 3, is adjusted to the constant circle 7 an when the grinding head 17 carrying the grinding wheel 15 is fed downward by the operation of the pinion and rack mechanism, the unground surfaces of the blades in the chuck will be engaged by the Wheel. The grinding Wheel rotates at high speed, while the chuck rotates at low speed. As the chuck rotates, the grinding wheel en ages the blades therein successively and grinds them all exactly to the constant circle 7, in asingle operation.

As'the wheel wears away, the head '17, carrying the wheel with" it, "is adjusted laterally by means ofthe screws 28 until the periphery of the wheel at one point coincides with the constant circle '7. The

change in the diameter of the wheel due to wear has no effect whatever uponthe radius of the constant circle andconsequently has rinding head 17 ofa well the grinding wheel.

blades are then re-introduced The pinion and- "rack' mechanism is operated by a handle :blades on each type being exactly no effect whatever upon the concavity of the blades, because it is therelative rotating movement of the chuck and wheel which controls the actual grinding-and so the blades will always be ground to the same circle, regardless-of the wearing away of When one side of the blades have been thus ground to the constant circle, the chuck is removed from its support and the ground blades are released therefrom by manually turning the eccentric clamping deviceslO less than half a revolution. The into the chuckwith their shanks extending in the opposite direction and are then clamped in position by a reverse manual operation of the clamping devices 10. The chuck is then reseated in its support 12 in reverse position. As aresult of this manual operation, the blade shanks lie Within the support as'theydidbefore, but the opposite sides of the blades are presented to the grinding. wheel. In the use ofthis particular apparatus, it is customary to have a spare chuck which the operator loads with a series of blades already ground.on one side, while the apparatus is performing the initial grinding operation on another series of blades. Y i

As beards vary in stiffness, .so razor blades should vary in stiffness. For this reason it is customary to make high-grade razors of three different degrees. ofstifi' ness, and this result is obtained by varying the concavity of the blades in the difierent types, thus varying their thickness. In the practice of the resent invention, this object is attained y utilizing three constant circles of different radii, all of the alike in form and in stiffness.

What is claimed is: The method of hollow-grinding razor blades which consists in positionin a blade Withone surface to, be ground slightly within a constant circle the radius of which is equal tothe radius of said surface when ground, then grinding said surface to said circle, and then reversely positioning the blade and similarly grinding the other sur face to the same circle. V

In testimony whereof, I have signed my name to this specification.

THOMAS o. SHEEHAN. 

